JPS58209045A - Electronic analytical device - Google Patents

Abstract

PURPOSE:To enable analysis with high accuracy while checking a drop in the S/N ratio under the influence of the primary electron rays by providing a deflection means between an electron gun and a charged particle detection device in order to intermittently deflect the primary electron rays and to intermittently irradiate a sample. CONSTITUTION:A deflection coil 36 serving as a deflection means is provided between an electron gun 11 and a charged particle detector. Accordingly, the primary electron rays 2 pass through plurality of detector 9 and an electrode 34 to irradiate a sample 3 while the primary electron rays 37 deflected by the coil 36 incide into the detector 38 and do not irradiate the sample 3. In this way, by intermittently deflecting the primary electron rays 37 to intermittenly irradiate the sample 3, stray electrons or the like due to the primary electron rays incide into the detector 9 to remove a disadvantage deteriorating the S/N ratio as well as to stabilize intensity of the primary electron rays with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an Auger electron analyzer that performs elemental analysis of a minute region on the surface of a solid sample.

A solid surface is irradiated with a primary electron beam of several keV, and the energy of the Auger electrons emitted from the -order muntin beam irradiation point is 2. Auger electron analysis method t'l, which analyzes the solid surface from the beam energy spectrum. It is widely applied as a type of direction analysis.

In general, it is known that the radiation yield in the Auger electron emission phenomenon when solid-state testing is irradiated with an f[n beam is Kokichi, which is a minute current of about 1×104 of the -order munton beam current. For this reason, it is necessary to use an electron Auger electron analyzer with a wide d, opening 1] angle in Auger electron analysis to increase the S/N ratio at the charged particle detection end.

FIG. 1 shows a conventional Auger electron analyzer.

1C1-order muntin radiation source, -order electron beam converging electron lens.

- A primary muntin beam corrad including a coil or electrode for secondary muntin beam deflection, 2 is a primary electron beam, 3 is a sample, 4, 6 and 6 are respectively cylindrical mirror electron energy analyzers (hereinafter cylindrical analyzers). (abbreviated as) outer cylindrical electrode and inner cylindrical electrode, 6.
7 Phantom: A slit cut along the circumference of the inner cylindrical electrode 5, 8 a slit for detecting electrons to be analyzed, 9 a charged particle detector 1, and 10 the trajectory of Auger electrons (electrons to be analyzed).

3-- In the Auger electron analyzer with such a configuration, the primary electron beam emitted from the electron gun and having its energy determined by the anode is focused and deflected by an electron lens, an excitation coil, etc., and is irradiated onto the sample 3. Ru. Some of the secondary electrons emitted from the surface of the sample 3 pass through the slit 6.7 on the inner cylindrical electrode 4 and the analyte electron detection slit 8, enter the charged particle detector 9, and the number of electrons is Detected as intensity.

Under these conditions, adjust the DC current or DC voltage applied to the deflection coil or electrode, fix the irradiation point of the -muntin wire on the sample surface at an appropriate position, and By sweeping the potential difference applied between the cylindrical electrode and the outer node electrode,
Among the electrons emitted from the sample surface, the energy of the electrons passing through the analyzed electron trajectory 10 within the cylindrical analyzer can be continuously changed.

The output obtained from the charged particle detector 9 by the above operation is amplified and applied between the inner cylindrical electrode and the outer cylindrical electrode.

An Auger electron energy spectrum can be obtained by displaying it in response to the swept potential difference.

As mentioned above, as an electron energy analyzer with a wide opening angle, a cylindrical analyzer with a double cylindrical electrode structure is used, in which cylinders with different diameters are coaxially arranged as shown in Figure 1. The geometric aperture ratio C of the slit of this analyzer [reaches 11% of the half-solid angle].

In the structure shown in FIG. 1, only a portion of the emitted Auger electrons are introduced into the charged particle detector 9, so the S/N ratio is not compromised.

Doo, Auger? The area resolution of the IL analyzer is 1 μt.
It is impossible with the structure shown in Fig. 1 to make the diameter smaller than nφ.

Therefore, in order to shorten the distance between the munton irradiation system and the sample volume and improve the area resolution, the electron beam from the electron beam source is transmitted inside the cylindrical analyzer as shown in Figure 2. A. Irradiating the sample along the axis of the cylindrical electrode: By adopting this structure, Auger electrons can be introduced into the cylindrical analyzer most efficiently.

In FIG. 2, the electron beam 2 generated by the electron gun 11 is transmitted through the first condenser lens 12 and the aperture 13.5°---
゛The sample 3 is focused by the second condenser lens 14, etc.
is irradiated. Auger electrons emitted from the sample surface 10
traces a trajectory as shown in the figure within the inner cylindrical electrode 6 and the outer cylindrical electrode 4, passes through the slit 15, reaches the charged particle detector 9, and is detected as the electron number intensity. By fixing the position of the electron beam irradiating the sample and sweeping the potential difference applied between the inner cylindrical electrode and the outer cylindrical electrode under these conditions, the trajectory of the Auger electrons passing through the analyzer can be continuously traced. It can be changed.

An Auger electron energy spectrum can be obtained by amplifying the output obtained by the charged particle detector 9 through the above operation and displaying it in response to the potential difference applied and swept between the inner cylindrical electrode and the outer cylindrical electrode. can. The spectrum thus obtained corresponds to micro area analysis.

The biggest problem with this Auger electron analyzer is -
It is located at the intersection of the second muntin beam 2 and the Auger electrons that have passed through the slit 15 of the analyzer.

That is, the scattered electrons flowing into the -order muntin line S') 15, etc. flow into the charged particle detector 9 and disturb the Auger electron signal, which is the minute current described above.

The present invention solves this problem by providing a deflection means between the electron gun and the charged particle detector and intermittently deflecting the -order muntin wire. The present invention provides an apparatus that improves sensitivity more than the conventional force method by irradiating a sample intermittently and removing noise components that lower the S/N ratio, such as scattered electrons due to -order munton beams.

FIG. 3 shows a schematic configuration of an electronic analyzer according to an embodiment of the present invention, and the same parts as in FIGS. 1 and 2 are designated by the same numbers 117.

The electronic analyzer 30 is evacuated by a vacuum bonder 31. A current is supplied to the electron gun 11 from the high-voltage power supply section 32 to the surface of the sample 3 placed therein, and a second muntin wire 2 is generated. The primary electrons emitted from the electron gun 11 are converged by a converging electron lens system 33, and then pass through a plurality of hollow charged particle detectors 9 and a slit system 16.
Inside 3 of inner cylinder' electrode 6 of cylindrical mirror type energy analyzer
4 and enters the primary electron irradiation point 35 on the test beak 3.

In steps 1 to 1, the -order muntin beam 2 is intermittently deflected by a deflection coil 36 serving as a deflection means, and only when the deflection is not activated, the primary electron beam 2 passes through the plurality of detectors 9 and the electrodes 34.
The sample 3 is irradiated through the inside. When deflected by the coil 36, the primary electron beam is bent 5, and the deflected primary electron beam 37 enters the detector 38. That is, the Auger electrons 1o generated from the sample 3 by the irradiation with the -order muntin beam pass through the convergence point 39 and pass through the electron trajectory 40 to the detector 9.
However, at this time, the primary electron beam 37 is deflected by the deflection coil 36 and enters the detector 38, and is not irradiated onto the sample 3. In this way, by intermittently deflecting the -order muntin line 37 and intermittent irradiation of the sample 3, scattered electrons and the like based on the -order muntin line enter the detector 9, thereby increasing the S/N ratio. It is possible to eliminate inconveniences that cause deterioration.

The primary electron beam 37 is deflected by the deflection coil 36.
enters the detector 38 and is read out by the ammeter 41, then
The signal is sent to the feedback circuit section 42 to the power supply section 32. With this configuration, it is possible to constantly monitor the intensity of the -order muntin wire, detect changes in the intensity, and control the output of the power supply unit 32 according to the change, making it possible to conduct accurate analysis. The intensity of the primary electron beam, which is one of the most important items in obtaining data, can be stabilized with high precision.

Now - Auger electron 10 generated from the next muntin irradiation point 35
The electrons pass between the inner cylindrical electrode 5 and the outer cylindrical front electrode 4 while drawing an analyzed electron trajectory 40, pass through the slit system 15, and reach the plurality of charged particle detectors 9. A high frequency rectangular wave current 44 tuned to an oscillator 43 is passed through the deflection coil 36 to intermittently perform deflection.

Confidence of charged particle detector 91. Through preamplifier 45,
Signal amplification is performed by a fin amplifier 46 in tune with the oscillator 43. Then, the inner cylindrical electrode 5 is electrically grounded 12, and the voltage applied to the outer cylindrical front electrode 4 is scanned.
By reading out the output of the long-in amplifier 46 and outputting it to the x-y recorder 47, an integral type electron energy spectrum is obtained.

48 Ren 1, lamp power supply.

9.

The spectrum obtained in this way becomes a micro area analysis. Note that an electron lens system 49 consisting of a condenser lens, a deflection coil, an objective lens, etc. is housed inside the inner cylindrical electrode 5, so that the distance between the objective lens and the sample 3 can be brought closer.

According to the apparatus shown in FIG. 3, since Auger electrons are introduced over the entire circumference of the cylindrical mirror energy analyzer, the signal yield can be increased.

The blurring of the diameter of the primary electron beam on the sample surface is determined by spherical aberration, which determines the spatial resolution of the Auger electron analyzer. Spherical aberration is proportional to the square of the objective lens-sample distance. With the structure shown in FIG. 3, it is possible to bring the objective lens and the sample close to each other, and the spatial resolution can be significantly improved over that of the conventional scanning Auger electron analyzer. Furthermore, with the structure shown in Figure 3, the size of the sample is no longer related to the cylindrical analyzer, there is no restriction on the diameter of the sample to be analyzed, it is possible to mount a large-diameter sample, and the overall size of the device is improved. There are advantages such as miniaturization.

The primary electron beam is intermittently irradiated onto the sample surface using a deflection coil, and charged particles are detected in synchronization with the interruption of the -order muntin wires, so scattering of the -order muntin wires, etc. It is possible to reduce the noise component caused by Therefore, S/
The N ratio can be significantly improved, and the detection limit has also been significantly improved.

According to the present invention, the resolution is immediately 8,000 yen.
It is possible to reduce the size, prevent a decrease in the S/N ratio due to the influence of negative muntin lines, and perform highly accurate analysis.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a conventional electronic analyzer, FIG. 2 is a schematic cross-sectional view of another electronic analyzer, and FIG. 3 is a schematic cross-sectional view of an electronic analyzer according to an embodiment of the present invention. 2.37...- Next muntin beam, 3... Sample, 9... Charged particle detector, 11... Electron gun, 15... ...Slit type, 32...
High voltage power supply section, 36...Deflection coil, 38...
. . . Detector, 42 . . . Feedback circuit section.

Claims (2)

[Claims] (1) An energy analyzer and a plurality of charged particle detectors are disposed between an electron gun that emits a secondary electron beam and a sample, and the secondary electron beam is emitted between the charged particle detectors and within the energy analyzer. and a means for deflecting the -order electron beam is provided between the detector and the electron gun, and the deflection means intermittently irradiates the sample with the -order electron beam. Analysis equipment. (2) The electron analysis device according to claim 1, further comprising a device for detecting the deflected primary electron beam and controlling the power output of the electron gun.